Posts Tagged ‘biasing’

Does Plate Dissipation Affect Valve / Tube Life In Practice ??

Thursday, November 8th, 2012

In general, the obvious connection between higher anode dissipation and shorter tube life holds good, however,  many other factors affect tube life, including accuracy of heater voltages and the efficiency of tube cooling within amplifiers.

The tube leaves the factory with a known amount of cathode coating material which is the source of all the electron emission. In use, this material is used up as it emits electrons when heated by the filament and plate current is drawn.

If plate current is drawn before the cathode is at operating temperature, the surface of the cathode can be damaged (so called ‘cathode stripping’).

This is why the Standby switch should be off when the amplifier is warming up. If, however, the tube is operated for long periods with the filament hot with little or no plate current being drawn, then an oxide-like coating can form on the cathode, effectively blocking the emission of electrons even when normal operation is required (known as ‘cathode poisoning’). TubeSync takes care of this by automatically controlling the bias at both start-up and run conditions.

vacuum tube EL34 valve

Plate dissipation is generally quoted by the manufacturer as a maximum value which, if exceeded could cause damage to the tube and should not generally be used for ‘normal’ operation. The relationship between tube life and plate dissipation follows an exponential curve. Tubes operated correctly at around 30% maximum dissipation can have lives in the region of tens of thousands of hours and can last several decades of years. This figure decreases rapidly as the dissipation increases, in some cased down to hundreds or even tens of hours as they approach or exceed their maximum plate dissipation rating.

Cooling is extremely important as running tubes very hot also increases the risk of arcing and a condition known as thermal runaway, which can instantly destroy the cathode material, making the tube useless. Conventionally biased tubes are most at risk when biased towards ‘Class-A’ operation, as they experience maximum power dissipation when no audio signal is present.

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Orange Amps DIVO TubeSync and OV4 Explained

Thursday, April 21st, 2011

Orange Amps presents DIVO with TubeSync technology. DIVO helps increase the life of your tubes, protects against unexpected tube failure, and even allows for (4) different tube types to be installed in the same amp.

DIVO will come pre-installed on select Orange Rockerverb 100 MKII heads beginning Summer 2011. The OV4 stand-alone unit, also available in 2011, can be installed on almost any amp that has (4) power tube slots.

ov4_tubesync

Tube Amp Testing For Professional Stage Performers – Engineering Tube Talk

Tuesday, February 22nd, 2011

A common requirement for tube amplifiers used for professional and stage purposes is that there should be a high percentage of confidence that one or more tubes will not fail during the performance. Tubes are often thought of in the same manner as light bulbs, in that they are most likely to fail catastrophically at switch on. This means that the moments just after the switch on point constitute the most stressful and potentially damaging periods in the life of the equipment.

In an attempt to guard against this possibility, it is common practice to do one of two things on a regular basis.

1/ regularly remove the tubes and have them commercially tested;

2/ replace the tubes with new stock on a regular basis.

These two methods may give the operator a degree of confidence but in fact, it can be shown that the faith placed in both methods is misplaced.

It is a known fact that removal of a tube from its socket results in a number of potentially damaging mechanical stresses on the metal to glass seals around the pins. Each insertion of an all glass tube will cause micro-cracking of the glass around the pin. This will invariably cause a small leakage of air into the valve, causing ‘gassing’ and eventually leading to its demise.

Removal for testing will also break the intimate contact between the holder and the tube contact pin, resulting in a poorer contact on re-insertion.

Many tube testers apply unreasonable electrical stresses to the tube internal electrodes and it is not uncommon for a known good valve to be damaged during the test. Tube testers can also give erroneous results depending on the way they perform the tests, possibly allowing faulty tubes to show ‘good’ and the good valves to be rejected as ‘bad’.

The second method of ‘blanket replacement’ with new stock on a regular basis can also lead to problems because if the failure distribution curve for tubes is analysed, it can be seen to follow the classic ‘bathtub’ failure curve. This inevitably means that an amplifier which is regularly ‘re-tubes’ will inevitably be considerably more likely to fail during the first hundred hours service than one which has been left untouched.

TubeSync overcomes these problems by performing an ‘in circuit’ test on the tubes every time the amplifier is powered up. The mutual conductance (gm) of the tube is measured by monitoring the cathode current of each valve whilst adjusting the grid bias in fixed steps. The results are tabulated and the new value is compared with previously stored values. A decision is then made on how far the tube has decayed in emission since the last test. Outputs from the device inform the user of the predicted remaining life of the tube.

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TubeSync Facebook Friends Are Now 2,000+

Wednesday, February 16th, 2011

Due to the growing demand TubeSync has now over 2,000 friends on Facebook!

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Click on the link above if you would like to join the TubeSync Revolution

The Scissor Sisters Choose Hiwatt, Hiwatt Choose TubeSync

Friday, October 8th, 2010

The extravagant disco pop group The Scissor Sisters have purchased a Hiwatt amp for recording and live performances. They have just been announced as support to Lady Gaga for the North American leg of her Monsters Ball tour and have a new single “Any Which Way” out now.

scissorsist

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KBO Dynamics TubeSync Technology

Friday, September 24th, 2010

Introduction

There is a certain quirkiness about the British psyche. On the one hand, the proportion of consumers in this country who actually bother thoroughly to read instruction manuals is undoubtedly very low. On the other, there was a Japanese survey, apparently, that found of all significant inventions going back over 200 years, 55% of them were British. Obviously, the Germans are more disciplined and better organised. The Americans are driven. The Japanese are still incredibly advanced technically, yet the British struggle to get the trains running on time. Maybe that’s the point: because we’re surrounded by chaos, we’ve had to become inventive.

The Americans make the best electric guitars but the British make the best amplification, goes the old adage. Doubtless, there are as many British luthiers as American amp manufacturers chorusing their disagreement, but as a general rule, this is probably true. And although if you look at all the great British amp makers – Hiwatt, Marshall, Sound City, Orange and the rest – they all have an Achilles Heel: the tubes. Ironic, really; amps that collectively have been responsible for the greatest sounds in contemporary music relying on components whose design hasn’t altered at all for decades. Enter TubeSync.

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The engineering guys here at KBO Dynamics – inventors of TubeSync technology -are into power supply. Their background ranges from white goods to defence, and to be fair, making a washing machine go is hardly rock’n’roll. But when they turned their knowledgeable gaze towards tube amps, well, that’s different. For example, when a technician at Hiwatt builds a Custom tube amplifier, he and he alone will spend 20 hours soldering the components to stringent quality control guidelines: no production line or PCBs here. Yet, despite this labour of love, if the tubes fail, the amp won’t work. So when KBO Dynamics approached Hiwatt with a system that could monitor the tubes constantly when the amp is turned on, adjust the biases, forewarn if the tube was getting flaky and even switch pairs should one of the tubes fail completely, they pricked up their ears.

TubeSync

Musicians don’t shell out for a big, powerful expensive amp if they’re not gigging. That makes them either pro musicians or semi-pro at the very least. That also means that the public shell out to go and see them play. Therefore, neither party will be particularly chuffed if a tube goes in the middle of a performance. Yes, the pro musician probably carries a spare amp just in case, as most guitarists have a spare guitar in case they break a string, but it’s not ideal. TubeSync gives the musician peace of mind; simple. With TubeSync fitted in the amplifier, it’s a bit like having a dedicated amp tech working full time on that amp from the moment it’s turned on to the moment it’s turned off.

custom ampThe output from a traditional 100-watt valve amplifier comes from two pairs of EL34 tubes: matched 1 and 4, and 2 and 3. There are companies who sell ‘matched’ pairs of these tubes, as two identical tubes will tend to last longer than an unmatched pair. Normally, the EL34 will operate at 50Ma, although they can be rated higher, but the higher they are rated, the shorter their life. Best not to fiddle around too much, then. Better still, let TubeSync do what fiddling there needs to be done. The device, which is not an integral part of the amplifier, sits within the circuitry and ensures that the pairs remain matched throughout, and micro-adjusting the biases when necessary. Four LEDs on the facia plate – one for each tube – serve as a visual indicator of the state of each one. So the musician is given adequate warning if one of the tubes is getting flaky. In the unlikely event of one of the tubes letting go completely without warning, TubeSync will immediately switch out the affected pair; OK, the amp will be functioning at only half power, but at least it will be working. That’s peace of mind. Knowing that this technology is available but not using it would be a bit like driving really fast whilst wearing welding goggles. Don’t want to worry you or anything.

hayden Granted, having TubeSync installed in the amp is going to give peace of mind, but then we at KBO Dynamics haven’t just left it at that. Professionals in the music industry need to find out not only that there are certain strains on the tubes within the amp, but are there conditions within the live situation that perhaps put an amount of stress on the tubes above others. Handy that the techies can plug a laptop into TubeSync and get a readout, then. Handier still, we are working on an interface that when completed will allow the TubeSync-ed amp to hook up with either us or Hiwatt via the internet, and the amp’s performance can be monitored remotely in real time, even if the gig is in Australia. How formula 1 is that then? But then again, it isn’t, when you think about it; it’s more like professional progress. The Rolling Stones, for example, earn millions every time they tour – having seen them, they’re worth every penny, but that’s just one opinion – but they will never have toured in the past with amps loaded with TubeSync. Imagine the poor old amp techs frantically peering through the grilles of the back line checking for the dreaded EL34 red death glow while the band is laying it down for over a million fans on a beach in Brazil: now that’s stress.

We are talking with other amplifier manufacturers, but Hiwatt was a logical place to start: they are fiercely proud of their reputation for reliability, rightly so, and any technology that compliments that reputation is clearly going to be of interest to them. Both KBO Dynamics and Hiwatt feel that the incorporation of TubeSync technology genuinely adds value not just to the amplifier, but also to the whole amplification process. Tubes are still fairly reliable; with or without TubeSync, manufacturers wouldn’t build tube amps if they weren’t and we’re not in the business of scaremongering. However, the fact of the matter is that they are still the least reliable component part of the amp, and if you have experienced ‘sod’s law’, then you’ll know that if a tube is going to fail then it’ll pick the most inconvenient time to do so. Going back to the driving analogy, the odds of you needing the airbag in your car are reassuringly long. But try driving a car without one fitted, you genuinely do feel vulnerable.

Conclusion

In recent years, there has been an exponential rise in ‘extreme sports’ and the arrival of the adrenaline junkie, doubtless in response to an increasingly risk-averse society. The term “Nanny State” has been coined as a result. But let’s keep things in perspective; there’s a big difference in safety for safety’s sake and straightforward common sense. TubeSync technology has been designed to prolong the life of the tubes in the gigging musician’s amp – which is good – and also to alert them to the fact that the tube is approaching the end of its life – also good. We think that’s common sense, which is why we invented it.

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TubeSync Bias Engines Roll Off The Production Line

Friday, August 20th, 2010

Due to popular demand the TubeSync Bias Engine is now in volume production!

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For order enquiries please email sales@tubesync.co.uk

Never Hang Your Guitar Tubes / Valves Upside Down

Thursday, March 18th, 2010

Never hang your guitar tubes upside down as many horrible things may happen!!!

The heat from the electrodes will go directly to the base pins and cause problems with oxidization. The heat will also cause micro-cracks on the pins of the tube / valve, which could result in failures.

Don't_ hang_ your_tubesSo don’t do it !!…….

Hiwatt Underline Reliability Repuation With TubeSync

Thursday, February 18th, 2010

Famed for their legendary reliability and tone, Hiwatt have gone one step further in the reliability stakes by employing TubeSync® technology in their already bulletproof amplifiers.

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Over the last year, Hiwatt and UK based KBO Dynamics have developed their own version of a pioneering technology called TubeSync®, which Hiwatt will launch at Frankfurt Musikmesse 2010 in March. The technology has been developed in order to overcome problems associated with conventional tube amplification such as biasing, tube longevity and overall reliability. What the collaboration has achieved is to improve amplifier design without changing the fundamental amplification process yet retaining the classic Hiwatt tone and sound.

Although not an integral part of the amplification process, Tubesync® is connected to the heart of the amp’s circuitry, constantly testing and monitoring; it’s like having an amp technician working full time inside the box every time the amp is powered up. This technology eliminates the need for tube bias current matching, increases tube life by micro-adjusting the bias on each tube, predicts tube failure and can, in the event of a catastrophic tube failure, even run the amp at half power. The result is the eradication of many of the problems hampering conventional tube amplifiers and peace of mind for the musician wise enough to have taken this route.

KBO Dynamics Chief Exec Andy Fallon: “It has been a pleasure working with Hiwatt who have been extremely receptive to change and have embraced the new technology. They have seen the benefits it can bring to them and of course, their customers, and we are looking forward to further exciting collaborations. This technology genuinely has raised the bar concerning reliability and classic tube amps, and what’s more. It’s been developed exclusively in the UK .”

For more information on TubeSync® technology, please visit www.kbodynamics.com and www.hiwatt.co.uk.

Hiwatt produce classic British custom amps both guitar and bass.

Tube Failure Modes, Within Amplifiers

Tuesday, August 11th, 2009

Catastrophic Failures. These are failures that occur suddenly, without warning, making the equipment unusable.

Examples of catastrophic failures are: –

  • Glass failure, loss of vacuum due to mechanical damage or thermal stress.
  • Heater failures open circuit or partial short circuit due to excessive heater voltage or high initial surge current and normal on off cycling over many thousands of hours.
  • Arcing, due to low cathode temperature, causing damage to the cathode and grids.
  • Bias failure due to component leakage or valve characteristic spreads using fixed or auto bias.

Degenerative Failures. The slow but eventual, deterioration of all tubes, which can contribute to the end of life of the tube.

Examples of degenerative failures: –

  • Gas is present in all tubes and if the tube is used within its characteristics should not be a problem, however excessive dissipation can liberate gas from the tube structure and lead to eventual premature failure.
  • Getters are patches of evaporated metal, which are deposited on the inside of the glass. The purpose of the getter is to absorb any gas that may be evolved during the life of the tube and work best at normal glass bulb temperatures.
  • Spurious emissions are uncontrolled unwanted emissions usually caused by gas released due to excessive dissipation and elevated temperatures.
  • Inter electrode leakage. This is current, which flows between the electrodes of the tube, which are not connected in any way. The cause is metallic vapours released by the hot metallic structure of the valve being deposited on the insulating micas and eventually leading to a conductive path.
  • Cathode depletion can occur due to arcing, which can strip the cathode coating reducing the active area of the cathode. Arcing will vaporise the cathode material and generate gas, which can poison the cathode material. This can also be caused, by passing excessive cathode current before the heater has reached its normal operating temperature.

Subjective Failures. These are tubes, which will normally pass tests but do not perform satisfactorily due to for example: – hum level, microphonics and noise.

Examples of subjective failures: –

  • Hum is an unwanted mains frequency signal, which is superimposed on the wanted signal.  It can be caused by heater to cathode leakage or due to electrostatic or electromagnetic fields within the equipment.
  • Microphonics is defined as a signal originating inside the valve caused by mechanical vibrations being amplified by the tube.
  • Noise is a signal originating from inside the tube, but not due to hum or microphonics. It can be due to intermittent short circuits, open circuits or arcing due to leakage paths between the electrodes.

Characteristic Variables. These are variations or spreads in the tube characteristics, due to manufacturing tolerances and follow a normal distribution curve.

Examples of characteristic variables: –

  • The Standard is usually a tube that complies with the manufactures published data. The Upper and Lower limits are values that any tube within these limits can be considered acceptable for normal use.
  • Characteristic Spreads is the degree of deviation from the standard tube.
  • Design Tolerances is the normal variations of standard parts, which a well-designed piece of equipment will operate correctly.

The Solution Is ……….TubeSync!

TubeSync Amp Biasing

TubeSync Amp Biasing


www.kbodynamics.com